Mercury retard switch



April 10, 1934. H. M. NACEY ET AL MERCURY RETARD SWITCH Filed Sept. 21, 1931 2 Sheets-Sheet l Mil/awn? #217 If #066 April 10, 1934. M NACEY r AL 1,954,364

MERCURY RETARD SWITCH Filed Sept. 21, 1931 2 Sheets-Sheet 2 629 @Mca Patented Apr. 10, 1934 UNITED STATES PATENT OFFICE MERCURY RETARD SWITCH Harry M. Nacey and Frank W. Jackson,

' Chicago, Ill.

Our invention relates to improvements in mercury retard switches or like devices.

The invention has particular reference to switch closing apparatus wherein the conducting terminals or electrodes at which the electrical contact making and breaking operations are effected are enclosed in a tubular member which contains a compact and coherent bow of current conducting fluid such as mercury, through the agency of which the said electrodes are brought into electrical contact making relation with each other. The invention relates particularly to switches of this type wherein mercury is employed as a current conducting fluid and wherein the purpose of the switch is to provide a retarded or delayed switch closing or opening action.

An object of our invention is to provide an improved mercurytube switch of the type described wherein a quantity of mercury is provided for the purpose of providing a delayed or retarded switch closing action.

A further object of the invention is to utilize the force of a mass of mercury in a tube of this type for urging a portion thereof through a restricted opening for the purpose of making contact between a pair of electrodes spaced from one another. I

A further object of the present invention is to provide an advantageous form of mercury switch or like device that is simple, practical and advantageous in construction.

A further object is to provide an improved switch of the type described wherein the weight of a body of mercury is utilized to force a portion thereof through a restricted orifice through which the balance of the mercury will not flow by reason of the diminishing weight of the mass thereof.

A further object is to provide an improved mercury switch capable of making a delayed connection between a pair of contacts and a quick or instantaneous break therebetween, or for making a delayed or retarded break and a quick or instantaneous connection.

Other objects and advantages will become apparent. from the following description wherein reference is had to the accompanying two sheets of drawings upon which Fig. 1 is an axial sectional veiw of the improved switch in a normal or rest position;

Fig. 2 is a similar view of the switch in a circuit closing position;

Fig. 3 is a view similar to Fig. 1 illustrating a modified form of the invention wherein the switch is utilized as a. delayed circuit breaking switch;

Fig. 4 is a changed position view similar to Fig. 2;

Fig. 5 is a vertical sectional view taken on the line 5-5 of Fig. 3; and

Fig. 6 is a fragmentary plan sectional view taken on the line 66 of Fig. 3.

As shown in the drawings, our improved switch comprises a tubular member 10 which may be of glass or other similar material usually employed for this purpose.

The member 10 is formed with a closing wall 12 at one end and a closing wall 26 at the other end. The wall 26 has an inwardly extending reduced wall portion through which a pair of conductors 16 and 18 pass and are connected at their outer ends with a suitable flexible conductor (not shown) which extends to any desired destination. A suitable filler F is placed in the interior of wall portion 14 to securely support conductors l6 and 18 as well as to hermetically seal the openings in the tube.

The conductors l6 and 18 are preferably formed with iron contact portions 20 and 22, the portion 22 being attached in a suitable socket 24 in the end of wall portion 14 and being bent and directed towards the end wall 26 of the member 10. The contact member 20 is seated in a tubular extension 28 formed in the socket 24 which serves to insulate the contact member 20 up to a point adjacent its outer end. The member 10 is formed with an integral dividing wall 30 at a point adjacent the center thereof which divides the tube into two chambers 10, and 10 The wall 30 has a tubular portion 32 extending toward the wall 12 of the member 10 and directed diagonally toward one of the side walls of the member 10. A reduced orifice 34 is also formed in the wall 30 during the formation thereof for a purpose to be hereinafter described.

The tube 10 is carried in a suitable cradle 36 that is mounted for pivotal movement upon a support 38. A felt or similar gasket 40 may be placed between the walls of cradle 36 and the walls of member 10 to avoid breakage. A quantity of mercury M is placed in the tube during the evacuating and sealing process.

In the preferred form of the invention, it is desirable to place a quantity of mercury in the tube greatly in excess of the amount required to provide a circuit making contact between the electrodes 20 and 22.

As is well known in the artQin the construc tion of mercury tube switches or similar devices, the chamber therein is ordinarily exhausted of air to form a vacuum therein. This is usually done for the purpose of preventing the oxidationof the mercury upon circuit making and breaking actions. However, in the construction of our switch, we prefer to evacuate the tube, as hereinbefore explained, and then place the mercury in the tube and fill the remaining space therein with hydrogen. The hydrogen or a similar gas thus takes the place of air and avoids a complete vacuum in the tube. With the assembly thus provided, a circuit making action will now be explained.

When it is desired to operate the switch to close a circuit through conductors 16 and 18, the switch is moved by any desirable mechanical or electrical force and tilted to the position shown in Fig. 2. Due to the weight of the mass of mercury in the tube, a portion thereof will be forced under this pressure through the restricted orifice 34 into the lower chamber 10 of the tube. The length of time consumed in forcing this mercury through the orifice 34 may be varied to suit the requirements of the mechanism upon which the tube is employed.

We have found by actual experimentation that a tube constructed generally in proportion to the tube shown in the drawings, will provide a circuit closing action which'may be varied from ten to thirty seconds.

Referring to Figs. 3 and 4, the construction has been modified to provide a delayed circuit breaking action instead of a delayed circuit making action. Accordingly a pair of electrodes 50 and 52 are directed into the end of the tube through wall 12. These electrodes are provided with contact making elements 54' and 56 which are preferably formed of iron. The tube 10 in this construction is formed witha closed wall 14 and the tube is adapted to be evacuated and filled with hydrogen and mercury from the end in which the wall 12 is formed. This construction may be as shown or similar to that shown in the preferred form at 14.

The action of the switch in opening a closed circuit is believed to be clearly illustrated in Fig. 4. Assuming that the switch has been tilted by any desired means to the position shown in Fig. 4, a quantity of the mercury will flow through the restricted orifice 34 until suchtime as the weight of the mercury remaining in the tube 10 becomes insufiicient to force any moremercury through the orifice 34.

One of the advantages of utilizing a larger mass of mercury than is required to fill the tube to make contact between the contact members, is that theaction of the mercury. in flowing to the contact points is absolutely accurate and the time limit for making a contact can be regulated to a very exact time interval. A further advantage lies in'the fact that there is a certain amount of deterioration and contamination of the mercury due to pitting or arcing when contacts are made or broken. Hence it is quite evident that with a larger body of mercury the possibilities of contaminating a large body are less than the possibilities of contaminating a smaller body, thus tending to provide a much longer life for the tube.

The manner in which the mercury is returned from chamber 10 to chamber 10 is believed to be clearly evident. When it is desired to break the circuit in the preferred construction, the

tube is tilted to a desirable angle with the wall 12 at the lowermost point. In this position all of the mercury in chamber 10 will, by action of gravity, flow into chamber 10 through the tubular portion 32 of the wall 30, thus quickly and effectively breaking the contact between elements 22 and 20. A similar action is employed in the operation of the modified form shown in Figs. 3 and 4 to effect a closing of the circuit through conductors 50 and 52.

It is believed to be apparent that numerous and varied uses can readily be found for our improved switch. The invention is capable of widespread use and we do not wish to be limited in the details of construction shown; rather what we desire to secure'and protect by Letters Patent of the United States is:

1. In a time delay device, controlling meanstherefor including a tiltable member having two chambers and a passageway connecting said chambers, a quantity of mercury in said member, said passageway being so restricted as to prevent the passage therethrough by its own weight of a suflicient quantity of mercury to operate the device, the amount of mercury in said member being sufiiciently in excess of the amount required to operate the device whereby upon tilting said member a suflicient portion of the mercury to operate the device will be forced from one of the chambers to the other through said restricted passageway by the pressure of the weight thereupon of the excess mass of mercury.

2. A mercury type retard switch comprising a tubular member, a wall in said tubular member dividing the same into two chambers, a tubular portion extending from said wall into one of said chambers, said wall having a small opening therethrough, a pair of spaced contacts disposed in one end of the tube, the small opening being so restricted as to prevent the passage therethrough by its own weight of a sufiicient quantity of mercury to close a circuit through the contacts, and a quantity of mercury in the tube sufiiciently in excess of the quantity required to close a circuit through the contacts, whereby upon a tilting of the tube a sufficient portion of the mercury to close a circuit through the contacts will be forced through said small opening by the pressure of the weight thereupon of the excess mass of mercury in the tube.

3. A mercury type switch comprising a tubular of a long narrow cylinder closed at both ends, a

wall in said tubular member dividing the same into two chambers, a tubular portion extending from said wall into one of said chambers, said wall having a small opening therethrough, a pair ,of spaced contacts disposed in one end of the tube, the small opening being so restricted as to prevent the passage therethrough by its own weight of a suflicient quantity of mercury to close a circuit through the contacts, and a quantity of mercury in the tube sufiicientlyin excess of the quantity required to close a circuit through the contacts, whereby upon a tilting of the tube a suflicient portion of the mercury to close a circuit through the contacts will be forced through said small opening by the pressure of the weight thereupon of the excess mass of mercury in the tube.

HARRY M. NACEY. FRANK W. JACKSON. 

